In just the past month we've had three injections of eye-popping auction news: the $1.3 billion value of the collector car auction market in the US last year, the fact that nine out of ten of the top getters were Ferraris - including a $38-million 250 GTO – and the $292-million flood at this month's Scottsdale auctions.

That can make it sound like things are well over the top at the very top, but classic-car valuation company Hagerty has created a tool to measure the overall strength of the classic car market beyond the auctioneer.

Called the Hagerty Market Rating, an algorithm processes 15 readings taken from eight categories to generate a numerical state of the market. Auction sales are one of those measures, but Hagerty says auctions only account for three percent of transactions. More important are sales between private owners, which are weighted more heavily. The final number additionally includes data points like price guide and insured values, and expert sentiment.

Plotted on a bell curve from 0 to 100, the numerical assessment is meant to offer an at-a-glance indication of where values are going, updated every month. Right now, the pointer shows we're plum in the middle of an expanding market, yet safely distant from a superheated one (in spite of the intergalactic values of a few Ferraris), which CEO McKeel Hagerty says is "a very healthy place."